Metal flaw detection liquid



METAL FLAW DETECTION LIQUID Loy W. Sockman, Los Angeles, Calif.

No Drawing. Application November 8, 1954 Serial No. 467,643

13 Claims. (Cl. 73-104) This invention relates to an improvedcomposition for visually detecting sub-surface surface-connected defectsand flaws in metals.

One object of the invention is to provide a new penetrant compositionfor use in visually detecting flaws adjacent metal surfaces. Anotherobject is to provide a penetrant composiiton which permits visualdetection of the most minute sub-surface cracks and defects in metals. Afurther object is to provide a new penetrant flaw detection compositionof which the excess is easily flushed off the metal surfaces by means ofwater. A still further object is to provide an improved penetrant liquidfor detecting sub-surface flaws in metals which discloses defectswithout the use of developers or mechanical processing other thanwashing off the surplus liquid. Another object is to provide a non-toxicpenetrant testing liquid.

These and other objects are attained by my invention, which will beunderstood from the following description.

I have discoveredthat the use of a saturated monohydric alcohol ester,particularly propyl, butyl, and amyl, of the higher fatty acids, bothsaturated and unsaturated, ina penetrant solution for testing forsub-surface, surface-connected defects in metals, gives greatly.improved sensitivity and ease of detection over the penetrantcompositions which have heretofore been used and are known in the art.By the term higher fatty acids is meant saturated and unsaturated fattyacids having from 8 to 20 like, including specifically palmitates,myristates, laurates,

oleates, caprates and caprylates, either as individual esters, or asmixtures of esters, derived from the commercial sources, give superiorpenetrant flaw detecting liquids. The alcohol or base constituent of anyof these esters may be any of the propyl, butyl, or amyl radicals,either separately or in mixtures. In some testing procedures the singleor mixed esters alone may be used but I have found that the testing forsub-surface flaws is greatly facilitated by dissolving in the ester ormixed esters a visible or a fluorescent dye which, of course, makes thedefects visually more apparent. I have also found that because of thehigh viscosity at testing temperatures of some of these dyed esters andester mixtures, which prevents quick spreading action over the surfaceof the metal, an inert diluent liquid may be used to advantage, thediluent having substantially no other effect than to lower the viscosityand permit spreading of the penetrant material in a non-viscous thinnerlayer on States Patent ice 2 V the metal surface to be tested. Thediluents which I find most satisfactory either separately or in mixturesare Stoddards solvent; chlorinated hydrocarbon solvents such as carbontetrachloride or trichlorethylene; and one or more of the butylalcohols.

I have found that the penetrant solutions above described are readilyremoved by flushing with water, both during the processes of the testingprocedure to remove the excess from the surface, as well as at the endof the test for removing any residual testing re-agents.

Illustrative of my invention are the following compositions: p

I. Normal butyl fatty acid esters (mixed), as derived from commercialcocoanut oil fatty acids, 98 parts by weight; and 2 parts by weight ofMeiford Red, a red dye, soluble in said mixed esters.

11. Normal butyl fatty acid esters (mixed), derived from cocoanut oilfatty acids, 99/: parts by weight; and, /2 part by weight of Fluorol7GA, a fluorescent dye soluble in said mixed esters.

III. Amyl oleate, 20 parts by weight; Stoddards solvent, 78 parts byweight; and Mefford Red, ester-soluble red dye, 2 parts by weight.

' I V. Isopropyl fatty acid esters (mixed), derived from commercialcocoanut oil fatty acid, 25 parts by weight; Stoddards solvent, 61 partsby weight; N-Butyl alcohol, 10 parts by weight; Petronate L, a sodiumpetroleum sulfonate, 2 parts by weight; and Mefiord Red, estersolubledye, 2 parts by weight Any dyestufi which is soluble or emulsifiable inoil, preferably red, or any oil soluble or emulsifiable fluorescent dye,may be used in my compositions. I have used Meffords Red, an oil solubledyestulf whose formula is said to be O-toluene-azo-xylene-azo-b-napthol.I have also used General Dyestuif Corporations Fluorol 76A for producinga fluorescent pentrant composition. Obviously, other dyes andfluorescent materials which are soluble or thoroughly dispersed oremulsifiable'in the penetrant esters may. be used. I

As a fatty acid ester emulsifier to facilitate'the re moval of thepenetrant liquid, I have used, for example,

Atlas G-1256, manufactured by the Atlas Powder Company, which is apolyoxethylene sorbitol ester of mixed fatty and resin acids; andPetronate L, manufactured by L. Sonneborn Sons, a sodium petroleumsulfonate having an empirical formula, C H SO Na.

In general, any of the emulsifiers known to be'suitable .for emulsifyingoil and water may be used, although I prefer to use one or the other ofthose mentioned. While in some of my compositions a small amount, notmore than about two parts per parts of solution, by weight, of asuitable emulsifier facilitates the removal of the excess penetrantliquid by flushing with water, or the cleanup of the tested pieces, itis pointed out that an emulsifier is not necessary, and water alone willsatisfactorily remove the excess penetrant liquid, including thespecified diluents of the fatty acid ester or esters, so that thepenetrant in the cracks and defects which are sub-surface but connectedwith the surface, will become visible by seeping or creeping out upon,the cleaned surface.

The ester materials used in my penetrant liquids may be made by wellknown esterification processes. Mixed esters of the higher fatty acidswhich are present in cocoanut oil may be prepared by crossesterification with an alkaline catalyst, whereby the glycerine isdisplaced by the lower molecular weight propyl, butyl or amyl alcohols,and the esters then separated from the glycerine 3 After standing for asufficient time to allow the penetrant liquid to spread into the surfaceconnected flaws, cracks and defects, the excess penetrant liquid iflushed off the surface by means of water, following which the coloredor fluorescent penetrant liquid, in the flaws, cracks, and defectscreeps out of the cracks and spreads to show up the defect.

The application is a continuation in part of my copending application,Ser. No. 229,517, filed June 1, 1951, now abandoned.

I claim:

1. A penetrant liquid for detecting surface-connected defects in metalcomprising an ester whose acid constituent is a higher fatty acidradical selected from the group consisting of palmitic, myristic,lauric, oleic, capric, and caprylic acids and Whose base constituent isa saturated monohydric alcohol radical having from 3 to carbon atoms;and from 0.5 to 2 percent by weight based upon said ester of a dyestulfdispersible in said ester.

2. A penetrant liquid for detecting surface-connected defects. in metalcomprising an ester whose acid constituent is a higher fatty acidradical selected from the group consisting of palmitic, myristic,lauric, oleic, capric, and caprylic acids, and whose base constituent isa saturated monohydric alcohol radical having from 3 to 5 carbon atoms;from 0.5 to 2 percent based upon said esters of 'a dyestuff dispersiblein said ester; and an inert nonaqueous diluent for said ester.

3. A penetrant liquid for detecting surface-connected defects in metalconsisting of from to 99.5 parts by weight of an ester whose acidconstituent is a higher fatty acid radical selected from the groupconsisting of palmitic, myristic, lauric, oleic, capric and caprylicacids, and whose base constituent is a saturated monohydric alcoholradical having from 3 to 5 carbon atoms; 0.5 to 2 parts by weight of adyestuif dispersible in said ester; and 0 to 78 parts by Weight of aninert non-aqueous diluent for said ester.

4. A penetrant liquid for detecting surface-connected defects in metalconsisting of a mixture of esters whose acid constituents are higherfatty acid radicals selected from the group consisting of palmitic,myristic, lauric, oleic, capric, and caprylic, and whose baseconstituent is a saturated monohydric alcohol radical having from 3 to 5carbon atoms; from 0.5 to 2 percent by weight based upon said esters ofa dyestuif disp ersible in said mixed esters; and a proportion of aninert diluent for said esters sufficient to lower the viscosity of saidmixture of esters and dye to facilitate spreading thereof.

5. A penetrant liquid for detecting surface-connected defects in metalconsisting of a mixture of 20 parts by weight of amyl oleate; about 2parts by weight of oilsoluble red dye and about 78 parts by weight ofStoddards solvent.

6. A penetrant liquid for detecting surface-connected defects in metalconsisting of 98 parts by weight of a mixture of esters whose acidconstituents are higher fatty acidradicals derived from commercialcocoanut fatty acids and Whose base constituent is normal butyl alcoholhol radical; and 2 parts by weight of a dyestufi dispersible in saidmixed esters.

7. A penetrant liquid for detecting surface-connected defects in metalconsisting of 99 /2 parts by Weight of a mixture of esters whose acidconstituents are higher fatty acid radicals derived from commercialcocoanut fatty acids and whose base constituent is normal butyl alcoholradical; and A; part by weight of a fluorescent 'dye dispersible in saidmixed esters.

8. A penetrant liquid for detecting surface-connected defects in metalconsisting of 98 parts by weight of a mixture of esters whose acidconstituents are higher fatty acid radicals derived from commercialcocoanut fatty acids and whose base constituent is isopropyl alcoholradical; and about 2 parts by weight of a 'dyestnlf dispersiblc in saidmixed esters.

9. A penetrant liquid for detecting surface-connected defects in metalconsisting of 98 parts by weight of a mixture of esters whose acidconstituents are higher fatty acid radicals derived from commercialcocoanut fatty acids and whose base constituent is amyl alcohol radical;and about 2 parts by weight of a dyestuff dispersible in said mixedesters.

10. In the process of detecting surface-connected flaws in metal, thesteps of coating the surface of the metal with a penetrant liquidcontaining a dyed non-volatile ester whose acid constituent is a higherfatty acid radical and whose base constituent is a saturated monohydricalcohol radical having from 3 to 5 carbon atoms; allowing the liquid tostand on the metal surface for a suflicient time to spread into surfaceconnected defects, water flushing the surface to remove excess liquid;and allowing the liquid in the flaws to spread over the flushed offsurface, whereby to make said flaws visible.

11. In the process of detecting surface-connected flaws in metal, thesteps of coating the surface of the metal with a penetrant liquidcontaining a dyed non-volatile ester Whose acid constituent is a coconutoil fatty acid radical and whose base constituent is a saturatedmonohydric alcohol radical having from 3 to 5 carbon atoms; allowing theliquid to stand on the metal surface for a sufficient time to spreadinto surface connected defects, water-flushing the surface to removeexcess liquid; and allowing the liquid in the flaws to spread over theflushed olf surface, whereby to make said flaws visible.

12. A penetrant liquid for detecting surface-connected defects in metalconsisting of from 20 to 99.5 parts by weight of an ester Whose acidconstituent is a higher fatty acid radical selected from the groupconsisting of palrnitic, myristic, lauric, oleic, capric, and caprylicacids, and whose base constituent is a saturated monohydric alcoholradical having from 3 to 5 carbon atoms; 0.5 to 2 parts by weight of adycstuff dispersible in said ester; 0 to 2 parts by weight of anemulsifier soluble in said mixture; and 0 to 78 parts by weight ofnon-aqueous diluent for said ester.

13. A penetrant liquid for detecting surface-connected defects in metalconsisting of from 96 to 99.5 parts by weight of an ester whose acidconstituent is a higher fatty acid selected from the group consisting ofpalmitic, myristic, lauric, oleic, capric, and caprylic acids, and whosebase constituent is butyl alcohol; 0.5 to 2 parts by Weight of adyestufi dispersible in said ester; and 0 to 2 parts by Weight of anemulsifier soluble in said mixture.

References Cited in the file of this patent UNITED STATES PATENTS2,298,432 Thompson Oct. 13, 1942 2,478,951 Stokely Aug. 16, 19492,667,070 Sockman Jan. 26, 1954 2,764,556 Sockman et al. Sept. 25, 1956OTHER REFERENCES AtlasSurface Active Agents-Pub. 1948 by Atlas PowderCompany of Wilmington, Del., Table 1.

Modern Polishes and Specialties (Johns), Chem. Pub. Co. Inc., Brooklyn,N. Y., page 299 (1947).

10. IN THE PROCESS OF DETECTING SURFACE-CONNECTED FLAWS IN METAL, THESTEPS OF COATING THE SURFACE OF THE METAL WITH A PENETRANT LIQUIDCONTAINING A DYED NON-VOLATILE ESTER WHOSE ACID CONSTITUENT IS A HIGHERFATTY ACID RADICAL AND WHOSE BASE CONSTITUENT IS A SATURATED MONOHYDRICALCOHOL RADICAL HAVING FROM 3 TO 5 CARBON ATOMS: ALLOWING THE LIQUID TOSTAND ON THE METAL SURFACE FOR A SUFFICIENT TIME TO SPREAD INTO SUFACECONNECTED DEFECTS, WATER FLUSHING THE SURFACE TO REMOVE EXCESS LIQUID,AND ALLOWING THE LIQUID IN THE FLAWS TO SPREAD OVER THE FLUSHED OFFSURFACE, WHEREBY TO MAKE SAID FLAWS VISIBLE.